Unlocking the Functional and Nutritional Potential of Microalgae Proteins in Food Systems: A Narrative Review

As the global demand for sustainable, nutrient-rich protein sources intensifies, microalgae have emerged as a promising alternative due to their unique biochemical, environmental, and functional properties. This narrative review synthesises the nutritional value, protein composition, functional behaviour, processing technologies, and food applications of microalgae proteins. A literature search was conducted using PubMed, Scopus, and Web of Science, with keywords including "microalgae proteins", "nutritional value", "functional properties", and "alternative protein sources". Priority was given to peer-reviewed articles from the past decade that addressed nutritional quality, extraction methods, and food applications. Key species, Spirulina, Chlorella, Nannochloropsis, and Haematococcus, are highlighted for their high protein content (up to 70% dry weight), complete amino acid profiles, and rich bioactive compound content. Microalgae proteins show excellent solubility, emulsification, gelation, and foaming abilities, enabling use in dairy alternatives, baked goods, snacks, and 3D-printed foods. Advances in extraction, purification, and protein modification have improved their functionality, while cultivation on non-arable land and integration into circular biorefineries enhance sustainability. Remaining challenges include scalability, sensory optimisation, and regulatory clarity. Future studies should focus on improving sensory acceptance, optimising cost-effective processing, and expanding consumer awareness. Overall, microalgae proteins offer a robust and eco-efficient solution to meet global nutrition and sustainability goals.